Soft-start/stop sump pump controller

Abstract

A sump pump control includes a microprocessor that sends a trigger pulse to an alternistor to turn the alternistor on and connect the sump pump to an NC power source. The microprocessor also monitors the power source to find a positive / negative crossover point. The microprocessor adjusts the trigger to apply full power to the pump motor during normal operation and delays the trigger to apply reduced power for a soft start and soft stop. The microprocessor also triggers an alarm in the event of failure of the device, including failure of the alternistor or the microprocessor.

Description

[0001]The present invention relates to a solid state control for a sump pump, and in particular to a control that provides a soft start, a soft stop, and a warning in the event of various forms of failure, including failure of the controller itself.BACKGROUND OF THE INVENTION[0002]Sump pumps are required in all present and new construction that is below grade level. The sump pump prevents the build up of water around the foundation. This prevents the water pressure from building up and cracking the foundation or leaking into the basement and causing water damage. To prevent this damage, perforated drain tile is placed around the basement footing which allows the water to seep into the tile and gravity feed to a sump pit. The sump pit contains a pump that is used to discharge the water away from the foundation. In some construction, an additional sump pump may be provided to pump water from a washing machine into the main sanitary sewer system. Generally, sump pump pits are from 15 t...

AI Technical Summary

Benefits of technology

[0007]Control of the sump pump motor is by means of an alternistor. The alternistor is a solid-state switch similar to a triac but specifically designed to control inductive loads. The alternistor is triggered by the microprocessor each half cycle of the line voltage to provide both a soft-start and a soft-stop. The soft-start feature helps to reduce the inrush start up current, reduces stress on the motor bearings and especially reduces the start up impact stress upon the impeller blades that are usually made of plastic. The soft-stop feature allows the pressure in the discharge line to be gradually reduced until it equals the head height of water pressure in the discharge line and the flow just begins to reverse direction. At this point, the one-way check valve closes softly with reduced water hammering and subsequent pipe vibration.

Problems solved by technology

This alarm might indicate that the pump is not turning, the impeller is broken, or the discharge line is blocked.

However, the upper water level alarm will also signal a failure as the sump pit fills up with water.

A more serious condition occurs if the alternistor fails in a shorted state, as the sump pump motor will continue to run.

This condition will empty the sump pit and, without surrounding water, the motor will eventually overheat and possibly burn out.

Should the power supply voltage fail or the AC power be lost, the microprocessor will also cause an alarm to sound.

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